No, the simple fact of why we book those lessons - because nothing else is nearly as effective in improving our dancing.
Now I'm certain that you don't know what you're writing about.
One thing matters most in a dancer's development: time on the floor, both alone and with a REAL partner.
It is the student - not the instructor - who determines the effectiveness of the lesson.
I don't address this topic based on mere speculation. Years ago, I found myself ignorantly playing the same shell-out-the-money game which you are trying to defend. When the idiocy of what I was doing became undeniable, I walked out on the spot - in the middle of the competition. I never worked with any of the people on whom I had been wasting time and money again.
A dancer with an amateur partner will develop far faster than ne who only dances with professionals. One reason for this advantage is that, by sharing expenses, the two dancers can afford more time on the floor and more lessons together. They realize ten times as much of their full dance potential.
Atlanta has been overrun by pro/am; every major studio pushes it. I used to hear all of the time from women who "couldn't afford to practice with their pro and wanted to work with an amateur as well." The aim of this gimmick is to sell more lessons for the pro. When I added a note to the sites that I use that I was not interested in a pro/am tramp, the responses stopped.
When you compare the actual amount of usable knowledge transfered from an overpaid "expert" when compared to that from many more moderately priced instructors, the exhorbitant cost cannot be justified.
There are many first-class instructors who keep their fees low, rightly confident in the knowledge that they will always have plenty of business. When Terence was in Atlanta (and I consider him to be a top quality teacher in spite of his occasional stuffiness), he offered rates that could be fairly described as a bargain.
Time is always a more important investment for any dance couple than money.

jj